Phillips AD12100/HP8 modding for open baffle 33000 Gauss+? - diyAudio
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Old 12th February 2011, 12:02 PM   #1
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Default Phillips AD12100/HP8 modding for open baffle 33000 Gauss+?

Hey Guys Since when I pulled out my km30 out of there baffle to save from the destruction of cyclone Yasi I Discovered since they have been sitting the tweeters had fallen out of them. So I have decided to try modding some Phillips drivers in between my horn projects for fun. These where a 2 minute impulse buy. I actually thought they where the much more desirable 100db M series. But they are actually a hi power version with a smaller magnet. 93db. Which is too low for my amps really. I am posting this thread all so because thee seems to be very little on them in open baffle only one older thread I found. I want to learn about driver parameters and how they can be changed with surround and magnet mods. These drivers are in exceptional condition. The photo's don't do them justice and where quiet cheap. They seem to have a very stiff surround more so I can imagine then the m series. I am expecting a hi bass roll off. I have ideas of making a surround from chamois leather and perhaps applying amorall to the surround to loosen them up if applicable. I still have yet to learn enough about specs and whats needed for open baffle.

Vintage Philips Fullrange Allrange Speakers Drivers (eBay item 110642533608 end time 06-Feb-11 21:00:39 AEDST) : Electronics

30 x 10mm Disc (Rare Earth) - Aussie Magnets

Please observe these rare earth magnets. They are 3661 Gauss and by simply removing the top alloy magnet plate at least 9 each side can by placed on top of the current magnet at about a cost of $200. I fear removing the magnets or even these plates a little for that matter. As I have read that removing the magnet from a Philip's 9710 ruins the magnet strength. I don't want to do that to these. But if I position 9 magnet's on top (In a flat circular fashion)I get nearly 33000 Gauss added to the original magnet!. So questions are please?

How would the 2 magnets interact? The neo's and the ferrite/ceramics. Would the neos flatten the originals? I am not even sure the poles would be in the right line. GOTO's use neos like this though. Would placing the bulk of the magnetic intensity more rear would ruin everything? Or would I end up with a crazy efficient speaker with exaggerated specs IE bigger mid peak less bass. Something more akin to a horn speaker. AND if so would loosening the spider and surround flatten off the response ? Some thing more akin to its bigger magnet brothers?

OK I really just posted this thread because this was a fun thing to dream about this morning and I am trying to make good on my stupid mistake of buying these. That and there in such superb condition . They have lived out west all there life. No corrosion at all.
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Old 12th February 2011, 12:51 PM   #2
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Neodymium Magnets Disk 1-9/16 x 2/5 'N50' - eBay (item 260735277949 end time Feb-14-11 19:18:17 PST) Actually I think I can even do much higher gauss for 120$
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Old 17th February 2011, 10:35 AM   #3
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Default Some specs on its bigger magneted brother

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I have been searching trying to understand the differences of the 12 inch Philip's drivers as well as searching for different neodeem magnets on ebay and wondering how to add them. Firstly from this link. Its obvious to see that the magnet is much larger in diameter . But what is not so obvious is that possibly it has a larger pole piece too. I was surprised to see the frequency response only averages at 93 to 95 db. And this driver assuming is less efficient then this. I can see why they are appreciated when you note how flat there frequency response is. There not designed for off axis listening like I suspect the 9710 is with its large 3 k peak.

As far as the magnets go. I imagine what help adding a very Strong cylinder neo magnet to the pole piece would do for efficiency. I am ever increasingly concerned about flattening the existing magnets even if I remove the top plate and break the magnetic circuit. I will be mounting them in a baffle soon for a test anyway. I will be disappointed if their are below 93 db sensitive.
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Old 22nd February 2011, 07:58 PM   #4
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Location: kansas city mo, and on occasion, around the world ...
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the '/HP8' would be like a higher power, or a guitar version, of the AD 12100.

i know how you feel, about changing the magnets,

however -

philips speakers are increasing in value,

to the extent that they

'probly should remain in original form.

then again, the magnets bolt on,

so they can be restored to their 'original form' rather easily ...

so -

have you picked out a machine shop yet?
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Old 22nd February 2011, 08:49 PM   #5
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Location: Copenhagen
Hi FatBat !
Adding more magnet strength will only give you higher ouput in the upper frequency range. So your version might actually be the best for an open baffle. Why dont you give it a try. 93 dB could be louder than you expect.
Thorsten Larsen
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Old 23rd February 2011, 10:03 AM   #6
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Are yea I was planing on getting little cylinder neo's and sticking them on and listening. I worked out I could hugely increase the efficiency. In guesumation anyway. Just sticking magnets even though very very strong magnets may not couple too successfully. I wouldn't want to take the original magnets off as I suspect it may flatten them. I would love to know what it takes to build a magnet energizer BTW. I would love to be able to recharge speaker magnets. I have searched but with little success. There not guitar BTW simply higher power versions which have a higher resonance 60hz in stead of 45. Not a bad thing . Considering adding a woofer below will add bass . And perhaps the higher roll off means more efficiency in the mid. Allso there treble rolls off faster at 10k which I think again is an advantage. I would rather listen to the treble of a tweeter then a whizzer.

These are in such good condition. I am cooling off on the idea of modding. Unless they sound bad then all bets are off. I thought changing surround to chamois would be good. That turned out to be stupid as I have learned that open baffle speakers need stiff surrounds not loose ones. So I will keep reading and learning. I came tonite to post about getting some budget test equipment. I think its the next logical step to my speaker modding. Test them first I think.
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Old 28th February 2011, 03:14 PM   #7
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picked up a set of matching woofers for low end!
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Old 3rd March 2011, 05:01 PM   #8
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6moons audioreviews: Jamo Reference 909 check these me to jamo open baffles. Look like they bought those neo's off ebay and just stuck them on lol

Jamo making open baffles. That the last straw. Prolly cost 10k too. When I started with open baffle Je labs had just build his. Know there every where you look. Romy's right. There silly I am so over them I am going to build these and ebay them to some stereophile reading ebayer. The phy's km30's can go too.
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Old 4th March 2011, 07:40 AM   #9
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thats the problem with this site you get wasted and say something silly you cant edit it the next day when you sober up. but yea be nice to get ahold of those jamo drivers to try in a open baffle project.
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